But this energetic springer spaniel isn't from the police; he is the NHS's first and only drugs sniffer dog.

Drugs, guns and money

Formerly part of the Met's Marine Dog Unit, Paddy was trained from a puppy to track down illegal drugs, guns and money for the police.

Patients who take illegal drugs don't recover as quicklyChris O'Connor, Head of Nursing Practice

But after a clash of personalities with a kennel mate, he was moved two years ago to take up his position in the NHS workforce at the South West London and St George's Mental Health NHS Trust.

And two years on, the Trust claims the experiment has proved to be a success, with the number of drug finds dropping by two thirds since he began patrolling the wards in May 2010.

Operating across several hospital sites in South West London the Trust offers in-patient treatment for a broad range of mental health disorders.

And, as in any mental health trust ,there is an ever-present problem of illegal drug use.

This is particularly problematic when you are trying to treat mental illness, explains Chris O'Connor, Head of Nursing Practice at the trust.

"We know that patients who take illegal drugs don't recover as quickly and our aim is to get patients back into the community as quickly as possible."

Paddy and his handler, Julie Traynor

He adds "Someone like Paddy can help because he will help find those drugs, and also maybe identify patients that we didn't know had a drug problem, so we can then work that into their treatment plan."

Because of the negative impact illegal drugs may have on recovery, their use is specifically prohibited in patients' treatment plans.

Before Paddy arrived at the trust, nursing staff would have to search the wards & patients' belongings themselves.

But this was time consuming, taking staff away from their therapeutic duties, says Paddy's handler Julie Traynor. Paddy can perform the same job "in a matter of minutes".

And she adds that it's a less invasive way of performing a necessary task.

"The patients get to know him, they welcome us when he comes onto the wards, they know his name, they take no notice of me, they are all interested in saying 'Hi' to Paddy."

"We are seen to be doing a routine search, this is just part of how this trust manages its security issues."

And he is certainly efficient. To help demonstrate Paddy's skills Metropolitan Police officer Mark Mills is on hand to supply some contraband. A small packet of cocaine is hidden in the jacket pocket of a hoodie, which is left on the bed in a jumble of clothes.

Super sleuth

Julie releases Paddy and like a furry whirlwind he scours the room, poking his super sensitive nose into everything in search of his prize.

Finally he forages through the contents of the bed and as soon as his snout slips into the hoodie pocket he freezes, his sudden uncharacteristic inactivity indicating a find.

"A dog's sense of smell is at least 200 times better than ours" Mark Mills explains." A dog wants to go back to his roots and hunt for things and we utilise this, but rather than hunting for food he is now hunting for something else, be it drugs, guns, money, explosives, we just transfer it across."

As well as reducing the amount of drugs on the wards, the Trust also claims that Paddy's presence has helped cut incidents of violence against staff. In the two years he has been on duty this has fallen to the lowest level in five years - less than half the national average for mental health trusts and the lowest of any mental health trust in London.

But Julie believes that having Paddy around has other advantages.

"There is a therapeutic benefit of having a dog coming onto the wards and just visiting with the patients. I see how much he cheers people up and he is a change to the daily routine; that was a benefit that I hadn't expected to see."

Being Paddy's handler is a full-time job for her. He lives with Julie and she even moved house to fit in his 8 ft by 12 ft kennel.

"It's had quite an effect on my social life," she says, "I can't leave him for more than five hours, so its difficult to go to some social events, but I can't really take him with me because he sniffs out money too and he'll be going over people's bags all night."